Donating peace is just metaphor. It means radiating peaceful vibrations from your own self to influence other people to resonate in the same vibrations.
But this is possible only if you exist in your own self in the consciousness of Peaceful source by creating the thoughts and generating the respective corresponding feelings. Exercising mentally in this way will not only develop peaceful feelings in your self but also influence other people near you to feel peace.
I have learnt from Brahmakumaris Organisation that we can help others getting peaceful while in disturbed circumstances, by being in the existence of peaceful soul as point of light and spreading positive and peaceful vibrations all around in the environment and this exercise works as per the strength of the vibrations released. During this exercise, we meditate and connect to the Supreme Soul who is the Ocean of Peace and Power and withdraw the vibrations to be spread to others and even Nature's five elements - Prakariti.
Same way, we can also help the environment by helping all the five elements of Nature - Earth, Air, Akash, Water, Ether by our powerful and peaceful vibrations to let them become pure and in return help the mankind and other living beings.
If you want to learn meditation from brahmakumaris, check your nearest center at www.brahmakumaris.com